21-11-2012, 01:03 PM
The Regulation and Expression of gene activity
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Regulation and expression of gene activity
The regulation of gene activity is the best controlled at level of gene transcription.
We can better understand the regulation of gene expression in procaryotes by discussing the lactose(lac) operon of E.coli.
The control of gene expression
Each cell in the human contains all the genetic material for the growth and development of a human
Some of these genes will be need to be expressed all the time
These are the genes that are involved in of vital biochemical processes such as respiration
Other genes are not expressed all the time
They are switched on an off at need
Operons
An operon is a group of genes that are transcribed at the same time.
They usually control an important biochemical process.
They are only found in prokaryotes.
Jacob monod model
It is the control for the lac operon.
1.Repression of mRNA synthesis from lac operon
2.Induction of mRNA synthesis
3.Positive control of enzyme synthesis
Gene regulation
- Genes function as templates for the transcription of mRNA and using protein synthesizing machinery of the cell (ribosomes), the mRNA directs the synthesis of polypeptides in translation.
- z,y,a – operate single unit of transcription initiated at ‘a’
- Transcription of operon is both negatively and positively controlled.